The tiniest surviving baby named Saybie was born in 23 weeks and three days in a California hospital instead of 40 weeks - normal maturity period for any pregnancy. She weighed seven grams less than the previous smallest surviving newborn, who was born in Germany in 2015, according to the hospital.
Babies born before 28 weeks are considered micro preemies.
Baby "Saybie" was born prematurely when her mother was only 23 weeks into the pregnancy.
Now four months old, Saybie weighs 1.8 kg.
Saybie's family have given permission to share her story, but chose to remain anonymous.